chemical engineering MCQs – Page 108

Practise multiple-choice questions from chemical engineering for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

chemical engineering Mcqs

2141. ______________ column is the most suitable for achieving the best performance for mass transfer operations involving liquid with dispersed solids ?
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A. Spray

B. Wetted wall

C. Packed

D. Plate

2142. The wetted wall tower is used to determine_________________________?
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A. Individual mass transfer co-efficient (M.T.C.) in gaseous system

B. M.T.C. of liquid in liquid-gas system

C. M.T.C. of individual components in a liquid-liquid system

D. The overall M.T.C. of the system

2143. Agitator is provided in a crystalliser for____________________?
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A. Crystal growth

B. All A., B. and C.

C. Avoiding deposition on cooler surfaces

D. Formation of nuclei

2144. ______________ column is preferred to be used, when a high liquid hold up is required in a reactor for gas-liquid reaction ?
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A. Packed

B. Tray

C. Spray

D. Bubble

2145. Flights in a rotary dryer are provided to________________?
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A. None of these

B. Lift and shower the solids thus exposing it thoroughly to the drying action of the gas

C. Reduce the residence time of solid

D. Increase the residence time of the solid

2146. Raoults law is applicable to the_____________________?
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A. Real solutions

B. Non-ideal gases

C. Ideal solutions

D. Mixture of water and alcohol

2147. Pick out the wrong statement ?
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A. ther

B. Elutriation process refers to when the soluble material is largely concentrated on the surface of

C. Zirconia probe is used for the humidity measurement

D. insoluble solid and is simply washed off by the solvent

E. Cellulose acetate membranes are used in dialysis process

F. Cascade means a group of stages interconnected so that various streams flow from one to

2148. Fenske equation determines the __________________?
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A. Height of the distillation column

B. Optimum reflux ratio

C. Minimum number of theoretical plates

D. Maximum number of ideal plates

2149. Can a cooling tower cool water below the wet bulb temperature of inlet air ?
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A. Yes; but height of cooling tower will be prohibitively high

B. Yes; but the air flow rate should be excessively high

C. No

D. Yes

2150. Flooding in a column results due to___________________?
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A. Low pressure drop

B. Low velocity of the liquid

C. High temperature

D. High pressure drop

2151. Pick out the wrong statement ?
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A. Constant pressure distillation cannot separate an Azeotropic mixture

B. perature</strong>

C. Flash distillation is practised on wide spread scale in petroleum refinery

D. The relative volatility of a binary mixture at Azeotropic composition is unity

E. Relative volatility of a binary mixture changes appreciably with the minor change in

2152. Pick out the wrong statement?
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A. 1 Nm3 of dry air is lighter than 1Nm3 of humid air

B. The mass diffusivity, the thermal diffusivity and the eddy momentum diffusivity are the same

C. An Azeotropic mixture of two liquids has boiling point higher than either of them, when it

D. ws negative deviation from Raoults Law

E. fusivity

F. NSc = NPr= 1

2153. Dry bulb temperature of unsaturated air is more than its ________________ temperature?
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A. Dew point

B. Wet bulb

C. Both A & B

D. Neither A nor B

2154. In McCabe-Thiele method of theoretical plate calculation for a distillation column, the operating lines of stripping and rectifying sections coincide with the diagonal at ________________ reflux ?
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A. Operating

B. Minimum

C. Maximum permissible

D. Total

2155. In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as_____________________?
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A. Ri = (1 Re)/Re

B. Ri = Re/(1 + Re)

C. Ri = Re/(1 Re)

D. Ri = Re

2156. Pick out the wrong statement pertaining to leaching ?
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A. Very high temperature is not needed for the leaching of sugar beet

B. Door classifier can be used for leaching of coarse solids

C. Fine solids cannot be leached in a Pachuca tank

D. Vegetable seeds can be leached in either of Bollman extractor, Rotocel or Kennedy extractor

2157. In the absorption of ammonia in water, the main resistance to absorption is by the _________________ phase?
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A. Liquid

B. Gas

C. Both A. & B.

D. Neither A. nor B.

2158. For the case of flow of air past a wet bulb thermometer (air water vapour system), the approximate value of h2/ky.Cz is around____________________?
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A. 0.6

B. 0.24

C. 1

D. 0.72

2159. Fenske equation for determining the minimum number of theoretical stages in distillation column holds good, when the_________________?
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A. Multi-component distillation is involved

B. Mixture (to be separated) shows positive deviation from ideality

C. Relative volatility is reasonably constant

D. Mixture (to be separated) shows negative deviation from ideality

2160. Priming in a distillation column_________________?
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A. Is desirable from point efficiency consideration

B. Reduces the overall pressure drop

C. Is characterised by the presence of foam throughout the space between trays

D. Results from very low gas velocity

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